Concrete mixer



E. FREYSSINET CONCRETE MIXER Oct. 24, .1933.

Filed April 3, 1951 2 Sheets-Sheet 1 Oct. 24, 1933. E. FREYSSINET1,931,956

CONCRETE MIXER Filed April 3, 1931 2 Sheets-Sheet 2 Patented Oct. 24,1933 UNITED STATES PATENT OFFICE Application April 3, 1931, Serial No.527,573, and in France May 28, 1930 9 Claims.

It is known that removing gases from concretes and mortars improvestheir quality. The first attempts for creating a vacuum in a concretemixer after filling thereof have met with 6 great difiiculties due tothe cement dust that is 'drawn into the organs of the air pump. Thatdifilculty has been obviated by submitting the product to the action ofa vacuum after its wetting and partial or total mixing, which leads toallow the emulsion of air to be formed and then to destroy it.

My invention has for its object an apparatus which makes it possible todirectly manufacture concretes that are wholly free from air, and thatwithout it being necessary to use any vacuum pump in the ordinarymeaning of that word.

My apparatus essentially comprises a rigid receiver provided with a doorthat is made fluidtight by the external pressure so as to prevent theingress of air, said receiver being divided into two compartments by aflexible and extensible partition, made, for instance of india-rubber.

The outer compartment is adapted to receive gravel, sand, cement andwater which are mixed therein, while the inner compartment is adapted tocontain water which is forced thereinto or removed therefrom by means ofa pump so as to vary the volume of the outer compartment.

The whole forms a vacuum pump having a very high efiiciency in which thedoor plays the part of a check valve, and the flexible partitionactuated by water acts as a piston. The whole apparatus can be so movedas to thoroughly mix the materials introduced into the outercompartment.

A preferred embodiment of my device, given merely by way of example,will be hereinafter described with reference to the appended drawings,in which:

Fig. 1 is a diagrammatic vertical sectional view of my apparatus;

Fig. 2 is a horizontal section on the line 22 of Fig. 1;

Figs. 3 and 4 relate to different embodiments;

Receiver A, which has rigid walls, made preferably of sheet iron, hasthe shape of a body of revolution about axis X.X, and is adapted torotate about journals T, T1. Receiver A is provided with a door P actingas a check valve so as to prevent the ingress of air from theatmosphere. A rubber partition S is disposed inside said receiver so asto form an inner compartment C1 between itself and the wall of receiverA, and an outer compartment C. Said partition is fixed by its edge beingtightly held between the bolted parts A1 A1 which form receiver A, saidpartition forming a gasket between said parts. One of the journals T ishollow, which makes it possible to introduce water into compartment C1by means of a pump P and a coupling 1 connected to tank R located aboveit so as to prevent inflow of air and to permit rotation of Aindependently of P1. Pump P1 is adapted to convey a liquid, water forinstance, from tank R into space C1, or, on the contrary, from space C1into tank R, owing to the provision of a system of valves R1 and R2disposed respectively on the suction and delivery pipes of the pump.

At its upper part, receiver A is provided with a plurality of bars Qadapted to improve the mixing.

The operation of my apparatus is as follows:

Receiver A being so disposed that door P is at the top, said door isopened and cavity C is filled with gravel, sand, cement and water, inthe same manner as an ordinary concrete-mixer. The materials have atotal volume equal to V and contain in their insterstices a volume ofair equal to V1.

Door P is then closed and water is forced into cavity C1 so as to makethe volume of cavity C equal to V. Cavity C is then whollyfilled withthe materials to be mixed. The air, excepting that which is contained inthe interstices, escapes through the door.

Water contained between A1 and S is then drawn out until the volume ofC1 is substantially equal to zero. As door P forms a check valve whichprevents the ingress of external air, the air present in the intersticesof the materials expands in the space located above the concrete, at apressure equal to:

P being the atmospheric pressure,

V1 the total volume oi. the interstices in the materials,

V2 the decrease of volume of cavity C1.

Now, it is easy to operate in such manner that V2 may be very great withrespect to V1. A high vacuum is thus obtained. The concrete-mixer isthen rotated about its axis. The mixing is thus effected from the startin a partial vacuum that is sufiicient for practical purposes in mostcases. If, after some revolutions, the rotation of A is stopped in suchmanner that the door be dis posed at the top, and if water is introducedinto C1 until the pressure in C is equal to atmospheric pressure, itwill be found out that, due to the mixing, the volume of the materialshas become V: V and that the air originally present in the intersticesis separated from the concrete being formed By further admitting waterinto 0;, the volume of C is so reduced that water located above theconcrete may ooze through the joint of the door. In that manner, thewhole of the air is exhausted, excepting some bubbles that may bepresent in the concrete, and, eventually, the water in excess is alsoforced out. Said bubbles are very few, owing to the fact that the mixinghas taken place in a high vacuum.

By again emptying space C1 and rotating concrete mixer A, the mixing iscompleted in a vacuum approximately absolute vacuum. It would bepossible to still increase the degree of vacuum by a third, a fourthoperation, and so on, the amount of air remaining in the concretedecreasing, for each operation, according to geometrical progression.

When the mixing of the concrete and the removed of the gases have beencompleted, the door is opened in its upper position and the receiver istilted upside down. It is possible to facilitate the removal of theconcrete by means of a hydraulic device operated by the pump and whichalternately rases and lets fall one of the journals, T, or by means ofany other device producing shocks or vibrations.

My apparatus, as compared with ordinary con-' crete mixers, has not onlythe advantage of ensuring removal of the gases from the concrete, butthe following accessory advantages:

Cleaning is very easy, the rubber pocket being easily turned out and itsflexibility facilitating the removal of the cement that might have setduring the operation.

Wear and tear is very greatly reduced, owing to the great resistance ofindia rubber.

It is possible to force out together with air through door P a part ofthe tempering water that remains over the concrete, and therefore toexactly adjust the volume of water by eliminating the excess. Thisallows to place at the start the cement in presence of an excess ofwater so as to reduce the interstices in which air may remain, prior tothe beginning of the operation, and makes mixing easier.

Finally, according to my invention, the concrete mixer is easier tobuild and to drive owing to the fact that mixing is effected by a singlerotary motion about journals of normal diameter and disposed in the bestpossible position for avoiding projections of cement, the same rotarymotion also ensuring the bringing into position for filling the concretemixer, and also for discharging it, as opposed to the ordinary concretemixers which comprise multiple movements or circular supports mounted onrollers, which are useless with my apparatus.

It should be Well understood that the shape of the elements of myinvention may be difierent from what is disclosed in the above describedembodiment, any other flexible material may be substituted for indiarubber, and rotation about an axis may be replaced by any other methodof agitating the mixer, without departing from the principle of myinvention. In particular, the door may be provided with an automaticopening device, and it may be arranged in a different manner. The bottomof receiver A may be provided with a drain cock R3 for removing anytraces of air in compartment C1.

In the above described embodiment, fluidtightness of the door is ensuredthrough mechanical means, for instance by means of a hand wheel providedwith a screw and supported by a cross piece adapted to be secured inposition on the mixer. Such device obviously makes it necessary toperform a certain number of operations during the removal of the gasesfrom the mixture, in order to destroy fluid-tightness and thus allowgases and air to escape, or, on the contrary, to reestablish saidfluid-tightness during the mix ing operation.

One might also imagine a system of door working automatically in thesame manner as a valve, that is to say capable of being hermeticallyapplied on its seat as soon as the external pressure is higher than thepressure inside the concrete mixer, and of parting from said seat in thecontrary case. Such a door may for instance be made as shown in Fig. 3,where it consists of a metallic disk, provided at its periphery with arubber ring I.

In order that the action of the rubber may be 7 effective, it isnecessary that the seat U1 of the door on the concrete mixer should bemaintained very clean, and that result may be obtained by Washing saidseat with a certain quantity of water, for instance with waterintroduced into the concrete mixer for forming the concrete.

An advantageous arrangement consists in feeding said water through thesecond journal of the concrete-mixer into a pipe T2 integral with saidmixer and connected to an annular conduit Ta provided around the surfaceof the seat. Water flows onto said seat through holes T4 or a circularslot provided in said annular conduit.

The door may also consist of a mere disk of rubber V1 reinforced by ametallic ring V2, as shown in Fig. 4. Said disk is applied in -afluidtight manner against the edge of the aperture in the concretemixer, under the action of the vacuum produced in said mixer, or, on thecontrary it is moved away from it so as to allow air and gases to escapewhen the pressure in the concrete mixer is higher than atmosphericpressure. In this case also the seat of the door will be washed by waterflowing from an annular conduit.

Accessorily, deformation of the disk forming the door under the actionof the vacuum in the concrete mixer may be used for actuating, through asystem of rods, a locking mechanism adapted to prevent rotation of theconcrete mixer when, for some reason, the vacuum is not suflicientinside the concrete mixer, owing to defective fluidtightness of the doorfor instance.

By way of example, in the embodiment shown in Fig. 4, rod V; isoperatively connected with a lever 6 pivoted at 7 and which serves tomake and brake circuit 8. Said circuit is either the feed circuit of themotor that drives the mixer when said motor is an electric one, or theignition circuit of the engine that drives said mixer when said engineis of the internal combustion type. It will readily be understood thatthe parts can be so adjusted that circuit 8 will be closed only whenthere is a certain predetermined vacuum in the upper chamber of themixer.

Said locking mechanism will also be adapted to stop the movement of theconcrete mixer if during the rotation of the latter, the vacuum thatmust exist therein is destroyed for some reason.

In the general manner, while I have disclosed what I deem to be thepreferred form of my device, I do not wish to be limited thereto asthere might be changes made in the arrangement, disposition and, form ofthe parts without departing from the the volume of the first mentionedchamber, and

spirit of my invention as comprehended within the scope of the appendedclaims.

What I claim is:

1. A concrete mixer of the type described comprising in combination areceiver having the shape of a body of revolution about a certain axis,said receiver consisting of two elementssecured together along a circleat right angles to said axis, a rubber partition tightly held betweenthe edges of said elements, a circular aperture at right angles to saidaxis provided in one of said elements, whereby the materials for makingthe concrete can be poured through said aperture into the mixer, a doorfor closing said aperture bearing upon the outer 'edge thereof, meansfor strongly applying said door against said edge of the aperture in afiuidtight manner, two journals secured to opposite sides of the otherelement, one of said journals being hollow, whereby water can be forcedinto the compartment comprised between the rubber partition and the wallof the last mentioned element of the receiver or removed from to saidaxis provided in one of said elements,

whereby the materials for making the concrete can be poured through saidaperture into the mixer, a door for closing said aperture bearing uponthe outer edge thereof, means for strongly applying said door againstsaid edge of the aperture in a fluid-tight manner, two'journals fixed onthe opposite sides of'the other element, one of said journals beinghollow, a tank, a water pump, a pipe connecting said pipe to said hollowjournal, whereby water can be forced into the compartment comprisedbetween the rubber partition and the wall of the last mentioned elementof the receiver or removed from said space, so as to modify the volumeof the other compartment of the receiver, and means for rotating saidreceiver about said journals.

v 3. A concrete mixer of the type described comprising in combination, areceiver having rigid walls, a flexible partition in said receiver so asto divide it into two chambers, one of which is adapted to receive thematerials for making the concrete, means for forcing a liquid into theother chamber and withdrawing it therefrom, means,

provided in the part of the wall of said container that limits the firstmentioned chamber, for permitting the outfiow of gases from said chamberand preventing the ingress of external air thereinto, means foragitating said mixer, and means for sealing the first mentioned chamberwhen the mixer is to be agitated.

4. A concrete mixer of the type described comprising in combination, areceiver having rigid walls, a flexible partition in said receiver so asto divide it into two chambers, an aperture in the part of the wall ofsaid container that limits one of said chambers, whereby the materialsfor making the concrete can be poured through said aperture into saidchamber, a door bearing upon the outer edge of said aperture, means forstrongly applying said door against said edge of the aperture forsealing said chamber into fluid-tight manner, means for forcing waterinto the other chamber and. removing it therefrom, so as to vary meansfor rotating said mixer about a horizontal axis.

5. A concrete mixer of the type described comprising in combination, areceiver having rigid walls, a rubber partition fixed to the walls ofsaid receiver, so as to divide it into two chambers of variable volume,a circular aperture in the wall of said receiver on one side of saidpartition, whereby the materials for making the concrete can be pouredinto the chamber located on that side of said partition, means, adaptedto cooperate with said aperture, for allowing the outfiow of gases fromsaid chamber and preventing the ingress of air thereinto through saidaperture, and for tightly sealing the last mentioned chamber when thegases have been driven out therefrom, two journals on opposite sides ofsaid receiver, means for forcing .water through one of said journalsinto said receiver on the other side of said rubber partition into theother chamber and for removing it therefrom, so as to vary the volumesof the two chambers respectively, and means for revolving said receiveron said journals.

6. A concrete mixer of the type described comprising in combination, areceiver having rigid walls, a rubber partition fixed to the walls ofsaid receiver, so as to divide it into two chambers of variable volume,a circular aperture in the wall of said receiver on one side of saidpartition, whereby the materials for making the concrete can be pouredinto the chamber located on that side of said partition, a rubber linedcircular door bearing upon the outer edge of said aperture and adaptedto act as a check valve for allowingthe outflow of gases from saidchamber and preventing the ingress of air thereinto through saidaperture and for tightly sealing the last mentioned chamber when thegases have been driven out therefrom, two journals secured on oppositesides of said receiver respectively, means for forcing water through oneof said journals into said receiver, on the other side of said rubberpartition, into the other chamber, and for removing it therefrom, sothat the volume of the first mentioned chamber, which contains thematerials for making the concrete, can be alternately reduced, fordriving out the gases present therein, and increased for causing thegases present in the interstices of said materials to expand into saidchamber, and means for revolving said receiver on said journals.

'7. A concrete mixer of the type described according to claim 13 furthercomprising a circular pipe provided with an annular slot surrounding theouter edge of said aperture, which forms the seat for said door, andmeans for forcing water into said pipe.

8.A concrete mixer of the type described comprising in combination, areceiver having rigid walls, a rubber partition fixed to the walls ofsaid receiver, so as to divide it into two chambers of variable volume,a circular aperture in the wall of said receiver on one side of saidpartition, whereby the materials for making the concrete can be pouredinto the chamber located on that side of said partition, a circular doorcon sisting of a rubber disk, a metallic ring for reinforcing said disk,said disk bearing upon the outer edge of said aperture and being adaptedto act as a check valve for allowing the outflow of gases from saidchamber and preventing the ingress of air thereinto through saidaperture, and for tightly sealing the last mentioned chamincreased, forcausing the gases present in the interstices of said materials to expandinto said chamber, and means for revolving said receiver on saidjournals.

9. A concrete mixer according to claim 5, further comprising means forpreventing the rotation thereof on said journals as long as the pressurein the first mentioned chamber is above a certain value.

SSINET.

